Question

Given below are two statements :

Statement I : A speech signal of $2\text{kHz}$ is used to modulate a carrier signal of $1\text{MHz}$. The bandwidth requirement for the signal is $4\text{kHz}$.

Statement II : The sideband frequencies are $1002\text{kHz}$ and $998\text{kHz}$.

In the light of the above statements, choose the correct answer from the options given below.

• A. Both statement I and statement II are false.
• B. Statement I is false, but statement II is true.
• C. Statement I is true, but statement II is false.
• D. Both statement I and statement II are true.

Answer 1

The correct option is D Both statement I and statement II are true.

Sideband $=f_c-f_m$ to $f_c+f_m$

$=(1000-2)\text{kHz}$ to $(1000+2)\text{kHz}$

$=998\text{kHz}$ to $1002\text{kHz}$

Bandwidth $=2f_m=2\times 2=4\text{kHz}$

Hence, both statements are true.